A wired local area network is usually a broadcast type network where data transmitted from a node can be received by all the other nodes. Various nodes over the network share a channel, and this brings about great hidden risks of safety to the network. Once an attacker accesses and listens to a network, he can capture all the packets on the network and hence steal essential information.
Local area network (LAN) defined by the current [Chinese] National Standard GB/T 15629.3 (which corresponds to IEEE 802.3 or ISO/IEC 8802-3) does not provide any data secrecy method. In researches carried out in foreign countries, IEEE 802.1AE standard released by IEEE provides data encryption protocol to protect the Ethernet and makes use of hop-by-hop encryption safety measure to realize safe transmission of data between network nodes. However, such hop-by-hop encryption safety measure is only directed to the circumstance in which there is and only an encryption switching equipment between terminal user A and terminal user B, and cannot be applied in the scenario in which packets between terminal user A and terminal user B do not go through any encryption switching equipment, namely secret communication between neighboring user terminals. The protocol itself does not provide any secret communication mechanism between the neighboring user terminals.
As proposed by scholars versed in the art, a shared key could be established between neighboring user terminals via an authentication mechanism. Although such a method makes it possible to realize secret communication between neighboring user terminals without any encryption switching equipment, any two user terminals neighboring to each other establish a shared key by way of authentication in a local area network application, and this undoubtedly increases the network load.